North Korea is generally understood to have assembled a working nuclear weapons capability by 2006 , when it carried out its first underground nuclear test on October 9, 2006.

Quick context

Before that, North Korea had been developing the program for decades, including reactor work in the 1980s and major breakout steps in the early 2000s. It also publicly claimed in February 2005 that it had nuclear weapons , but the 2006 test is the clearest widely accepted milestone showing it had crossed into actual weapon testing.

Short timeline

  • 1950sā€“1980s: Early nuclear training and reactor development began.
  • 1993ā€“2003: North Korea withdrew from and then left the nuclear nonproliferation framework, escalating its weapons effort.
  • February 2005: North Korea announced that it had nuclear weapons.
  • October 9, 2006: North Korea conducted its first nuclear test.

Bottom line

If you mean when it first had nukes in practice , the safest answer is 2006. If you mean when it claimed to have them , that was 2005.